The present invention generally relates to surfactants that exhibit solubility in carbon dioxide, and systems utilizing the same.
The use of carbon dioxide as a clean, abundant, and tunable solvent is potentially environmentally beneficial, and accordingly it is being investigated in a number of applications including, for example, cleaning protocols, coatings, and polymer production and processing. See e.g., Wells, S. L.; DeSimone, J. Angew. Chem. Int. Ed. 2001, 40, 518. Notwithstanding the above potential benefits, carbon dioxide is often limited in that many materials such as water exhibit limited solubility therein.
In response to these possible solubility limitations, fluorosurfactants have been developed to potentially assist in the dispersion of water in carbon dioxide. See e.g., Harrison, K.; Goveas, J.; Johnston, K. P.; O""Rear, E. A. Langmuir 1994, 10, 3536, Johnston, K. P.; Harrison, K. L.; Clarke, M. J.; Howdle, S. M.; Heitz, M. P.; Bright, F. V.; Carlier, C.; Randolph, T. W. Science 1996, 271, 624, Eastoe, J.; Bayazit, Z.; Martel, S.; Steytler, D. C.; Hennan, R. K. Langmuir 1996, 12, 1423, Eastoe, J.; Cazelles, B. M. H.; Steytler, D. C.; Holmes, J. H.; Pitt, A. R.; Wear, T. J.; Heenan, R. K. Langmuir 1997, 13, 6980, Zielinski, R. G.; Kline, S. R.; Kaler, E. W.; Rosov, N. Langmuir 1997, 13, 3934, Eastoe, J.; Downer, A.; Paul, A.; Steytler, D. C.; Rumsey, E.; Penfold, J.; Heenan, R. K. Phys. Chem. Chem. Phys. 2000, 2, 5235, Lee Jr., C. T.; Bhargava, P.; Johnston, K. P. J. Phys. Chem. B 2000, 104, 4448, Lee Jr., C. T.; Johnston, K. P.; Dai, H. J.; Cochran, H. D.; Melnichenko, Y. B.; Wignall, G. D. J. Phys. Chem. B 2001, 105, 3540, and Liu, Z. -T.; Erkey, C. Langmuir 2001, 17, 274. Accordingly, water-in-carbon dioxide (W/C) microemulsions containing appreciable water quantities have been achieved, allowing for their use in a number of applications such as nanoparticle synthesis, organic reactions, voltammetric measurements, and enzymatic conversions. See e.g., Holmes, J. D.; Bhargava, P. A.; Korgel, B. A.; Johnston, K. P. Langmuir 1999, 15, 6613, Ji, M.; Chen, X.; Wai, C. M.; Fulton, J. L. J. Am. Chem. Soc. 1999, 121, 2631, Jacobson, G. B.; Lee Jr., C. T.; Johnston, K. P. J. Org. Chem. 1999, 64, 1201, Ode, H.; Hunt, F.; Kithara, S.; Way, C. M. Anal. Chem. 2000, 72, 4738, Lee, D.; Hutchison, J. C.; Demimonde, J. M.; Murray, R. M. J. Am. Chem. Soc. 2001, 123, 8406, Holmes, J. D.; Settler, D. C.; Rees, G. D.; Robinson, B. H. Languor 1998, 14, 6371, and Kane, M. A.; Baker, G. A.; Pander, S.; Bright, F. V. Languor 2000, 16, 4901. W/C systems have also been the subject of computational treatments. See e.g., Satanically, S.; Cui, S. T.; Cummings, P. T.; Cochran, H. D. Languor 1999, 15, 5188.
Nonetheless, inspite of any advantages of these systems, there remains a need in the art for surfactants and systems employing the same that allow for improved volatilization of various materials in carbon dioxide, such as, for example, water.
In one aspect, the invention provides a method of removing water from a first composition of matter. The method comprises contacting a first composition of matter comprising water with a second composition of matter comprising: (1) at least one surfactant comprising at least one phosphate group and (2) a solvent comprising carbon dioxide, wherein at least a portion of the surfactant is soluble in the solvent, such that the at least one surfactant removes at least a portion of the water from the first composition.
In another aspect, the invention provides a method of applying a surfactant to a substrate. The method comprises providing a composition of matter comprising at least one surfactant comprising (1) at least one phosphate group and (2) a solvent comprising carbon dioxide, wherein at least a portion of the surfactant is soluble in the solvent; and applying the composition of matter onto a substrate such that the carbon dioxide separates from the surfactant and wherein the surfactant coats the substrate.
In another aspect, the invention provides compositions of matter comprising (1) at least one surfactant comprising at least one phosphate group and (2) a solvent comprising carbon dioxide.
These and other aspects of the invention are described in greater detail herein.